A special TEM Li-ion battery sample preparation and application technique for investigating the nano structural properti
- PDF / 901,332 Bytes
- 7 Pages / 432 x 648 pts Page_size
- 5 Downloads / 175 Views
MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.262
A special TEM Li-ion battery sample preparation and application technique for investigating the nano structural properties of the SEI in lithium ion batteries Xiangyun Song1, Yanbao Fu1, Chengyu Song2, Philip Ross1, Vince Battaglia1 1.Energy Storage and Distributed Resources (ESDR) Department,
2.National Center for Electron Microscopy of Molecular Foundry, Lawrence Berkeley National Laboratory, University of California
Abstract: Herein we describe a technique for preparing samples from cycled Li-ion batteries with minimal contact with atmospheric water for examination by TEM and to provide the results of an analysis of the SEI in Li-ion cells. The electrode samples were prepared in a glove box by manipulation with a diamond tipped pen to carefully dislodge particles directly onto the TEM sample holder. Electrodes were extracted from Li-ion cells that contained a cathode of high capacity, manganese rich NCM (HCMR-NCM). Nanometer-sized MnF2 crystal particles embed themselves in the SEI layer of the anodes as observed and confirmed by HRTEM lattice image analysis and EELS. Cross-sections of the SEI layer reveal that the thickness of the SEI and propensity for MnF 2 crystal deposition is non-uniform.
INTRODUCTION: The preponderance of lithium-ion batteries (LIB) continues to grow exponentially as the applications expand beyond portable electronics to electric vehicles, military applications, and aerospace. [1-5] Research over the past 30 years continues to show that most of the failure can be associated with the imbalance of lithium in the cell as the result of an imperfect solid electrolyte interface on the graphite electrode [6-10]. As a result, it has been strongly suggested in many research papers that a better understanding of the nano-structure of the SEI through and around which ion transport occurs is critical for further advances. [11-15] A detailed ex situ analysis of this technology-enabling film 1
Downloaded from https://www.cambridge.org/core. University of Texas Libraries, on 01 Jun 2020 at 08:00:41, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/adv.2020.262
via TEM has proven difficult due to its chemical sensitivity to water, which is found in most laboratory environments. In this paper, we report a newly developed technique for sample preparation in which the electrode material and surface SEI layer of cycled electrodes experience minimal chemical reaction, contamination, or mechanical damage. Such samples were then studied for their micro- and nano-structure and compositional properties by high-resolution transmission-electron-microscopy (HRTEM) and electron energy loss spectrometry (EELS). It is worth noting that the impact on the anode of dissolved manganese that originates from Mn-containing cathodes is not fully understood. Many questions remain, where is the Mn located in the anode relative to the graphite surface? Does Mn complex with other atom
Data Loading...
